Transesophageal echocardiography (TEE) in addition to the conventional pressure tracing method may enhance a proper insertion of pulmonary artery (PA) catheter by providing information about the real-time location of catheter. We report a case of abrupt air leakage from the balloon of PA catheter during its advancement that was immediately diagnosed by TEE in 54-year-old male with moderate tricuspid regurgitation for elective CABG. Introducer and sheath of PA catheter were inserted in right internal jugular vein. After checking balloon function, connecting distal port to a previously zeroed transducer and confirming the location in right atrium, PA catheter was advanced under direct the visual surveillance by TEE images as well as pressure tracing. During the third trial of catheter advancement through tricuspid valve, multiple air shadows, which convincing balloon leakage, were appeared in right atrium in the view of TEE after inflation of air. We withdrew catheter immediately without any further effort of balloon inflation or advancement, then, balloon leakage and the incapability of balloon expansion were confirmed by saline injection, instead of air, into the balloon port. We replaced the injured PA catheter to new one, and advanced it successfully to the wedged position by the aid of TEE and pressure tracing. We assumed that TEE image might be a beneficial aid to enhancing PA catheter placement in a proper position and preventing possible complications or side effects produced by advancing it with unawareness or delayed recognition of its dysfunction.